Question

Solve: 0 = 4x2 − 8x − 5.

Answer 1

Try using the quadratic formula..

Answer 2

i always try the AC method first, here we have AC = 4(-5) = -20
so we want to numbers that multiply to -20 but add to -8 (the b value).
two such numbers are -10 and 2, then i expant the middle term using these numbers
4x^2 + 2x - 10x - 5 = 0 (notice is still the same thing that we started with)
then I factor something(the most I can) out of the first two terms so 2x devides both 4x^2 and 2x
2x(2x+1) then I want to factor something out of the 3rd and 4th terms such that what I have left is the same as (2x+1) so
2x(2x+1) -2(2x+1) = 0
then couple the terms
(2x+1)(2x-1) = 0
the solve
2x+1 = 0 x = -1/2
2x-1 = 0 x = 1/2

Answer 3

\[+-b \sqrt{b2-4*a*c}/2*a\]

Answer 4

All normal forms are good and work fine, the reason I tell people that are new to this to use the AC method is because it really lets you get a feel for factoring...which comes in handy later. I guess it depends on what you are doing in class.

Answer 5

I like that way, but what do you do next to get the fina answer? because 1/2 & -1/2 aren'y an answer choice

Answer 6

final*